The Green Mountain Boys were giants by the standards of the day, with an average height of 5 feet 10 inches.

UNWILLING TO MISS HIS OWN OPPORTUNITY for adventures, Scott managed to enlist as a fifer in the 3d Vermont Volunteer Infantry. In his enlistment papers he boldly proclaimed his occupation as "painter"- a vision of the future perhaps, but closer to the truth than his age, which the official register listed as 16, just old enough to allow admission as a fifer. Scott mustered into service with the 3d Vermont on May 16, 1861. Before the end of the month, he was on his way to the main encampment of Federal troops in Washington, D.C.The Green Mountain Boys were giants by the standards of the day, with an average height of 5 feet 10 inches. Onlookers crowded the streets of New York City as the Vermont troops marched through en route to Washington clad in fine uniforms, sprigs of pine affixed to their caps. Scott's oversized uniform half covered his hands, smothering the air holes of his fife whenever he played.

By August, the 3d Vermont was at Camp Lyon, guarding the Chain Bridge outside the Federal capital from nearby Confederate forces. Just four weeks after he had left Vermont, Scott saw an example of how serious a matter military duty was. A Private William Scott (no relation) of the 3d Vermont was found sleeping while on sentinel duty, and was sentenced to die. When the appointed day came, the 3d Vermont somberly fell in for the execution. Happily, however a reprieve from Lincoln arrived just in time, and was read to the cheering troops in lieu of the firing squad's report.

The letters Scott sent home describing his army experiences also provide the first glimpses of his art. His simple, linear pen-and-ink said more than his words. A sketch made during his regiment's initial foray into hostile territory, in September 1861 depicts an autumn view near Lewinsville, Virginia, with Munson's Hill in the distance. It shows a rolling countryside crisscrossed by rail fences, and a farm nestled in gentle surroundings, framed by trees in full leaf. As a child fascinated with art and things military, Scott had drawn Persian King Xerxes army on the march into Greece in 480 BC, using the back of a large map for the outside scene. Now, he had military themes from his own experience to translate into art.

By October 1861, Scott's regiment was part of the 1st Brigade of Brigadier General W.F. 'Baldy' Smith's Division , in the Army of the Potomac's IV Corps. Stationed at Camp Griffin in the Defenses of Washington, the brigade, which consisted entirely of Vermont units, suffered through the raw, rainy winter of 1861-1862, fully one fourth of the brigade was off duty because of illness. Relief finally came in March, with orders to prepare two days' rations and be ready to move. Scott and his comrades, now wearing army blue instead of their original gray, excitedly prepared to join the rest of the Army of the Potomac in one of the greatest military enterprises in modern history.